1. Field of the Invention
The present invention relates to the termination of telephone calls in a telephone network that provides privacy screening to its subscribers.
2. Background of the Invention
Private telephone numbers are telephone numbers that block services such as xe2x80x9ccaller IDxe2x80x9d that would otherwise identify the caller to the party he or she is calling (the xe2x80x9ccalled partyxe2x80x9d). A privacy screening service is a service that allows the subscriber to screen incoming calls. For example, a subscriber can choose to accept or reject an unknown call. In a telephone systems that offers private numbers and a privacy screening service to its subscribers, calls from a private number to a subscriber with the privacy screening service cannot be completed automatically, unless the caller grants permission to the system allowing the system to override the privacy of his or her number.
FIG. 1 is a schematic diagram showing the basic architecture of an Advanced Intelligent Network telephone system. The Advanced Intelligent Network System is described in U.S. Pat. No. 5,701,301 and U.S. Pat. No. 5,838,774, which are hereby incorporated by reference. FIG. 1 shows the caller""s telephone 101 which is connected via voice line 102a to its Service Switching Point (SSP) 103. SSP 103 is connected via voice trunk 102b to a second SSP (SSP 104). SSP 104 is the SSP that services the called party""s telephone 105. In this example, the called party is a subscriber who has subscribed to the privacy screening service. (The called party will be referred to as the xe2x80x9csubscriberxe2x80x9d as well as the xe2x80x9ccalled partyxe2x80x9d herein.) FIG. 1 also shows a Signaling Transfer Point (STP) 106 which services a Service Control Point (SCP) 107 and a third SSP (SSP 108) 108 which services a Service Node (SN) 109. SCP 107 has a database 107a which contains subscriber information.
STP 106 is a signaling hub that routes packets of data over the common channel signaling network. Signaling System 7 (SS7) is the protocol that runs over the common channel signaling network. The common channel signaling network using the Signaling System 7 protocol is commonly referred to as the SS7 network. The SS7 network carries data and control messages to the SSPs in the telephone network. SCPs are powerful fault-tolerant computers, e.g., ATandT Star Server FT Model 3200 or ATandT Star Server FT Model 3300 computers (these computers and more recent models such as the Advantage P200 and the Advantage 4P200 are available from Lucent Technologies). SCPs are xe2x80x9cintelligence centersxe2x80x9d with access to applications packages, software, routines and databases that enable the network to deliver advanced services such as caller ID, privacy screening and call forwarding. SNs are physically generally similar to SCPs, but include voice and Dual Tone Multi-Frequency (DTMF) signal recognition circuits and voice synthesizers. The operators of the telephone network can write software routines so that their SNs can manage data, perform digit collection, respond to calls, route calls as specified by the telephone network, and perform voice recognition functions. The SN""s voice circuits can be programmed to provide a voice response (e.g., to play pre-selected announcements) to callers. The SN can also be programmed to respond to input from the callers by, e.g., further routing the call.
As shown in FIG. 1, STP 106 controls communications between SSPs 103, 104 and 108 and SCP 107 over the SS7 data links. The SSPs are connected to the caller""s and the subscriber""s telephones and to each other via voice lines 102a and 102c and via voice trunks 102b and 102d. The SSPs can also communicate with each other over the SS7 data links shown in FIG. 1. The SSPs are also connected to and communicate with STP 106 and SCP 107 via SS7 data links 110a, 110b, 110c and 110d. SN 109 is connected to SSP 108 by an Integrated Service Digital Network (ISDN) Basic Rate Interface (BRI) line 111. Although FIGS. 1-2c only show one SCP and one STP, SCP 107 and STP 106 in FIGS. 1-2c generally represent two redundant SCPs and STPs, respectively, because it is preferable to have redundant SCPs and STPs in an AIN system.
FIG. 1a illustrates a prior art system for routing calls to subscribers to a privacy screening service. When a caller places a call to the subscriber, the call is routed by SSP 103 to SSP 104. FIG. 1a shows call 1 routed from the caller to SSP 103 and then to SSP 104. Because the subscriber has subscribed to the privacy screening service, that call (like all calls to that subscriber""s number) triggers a xe2x80x9ctermination attempt triggerxe2x80x9d or TAT. In response to the TAT, SSP 104 issues query 2, shown in FIG. 1a. Query 2 is a message that goes up to SCP 107 asking for directions as to how the call should be terminated. The query includes the following information: the subscriber""s telephone number (in the called party field), the caller""s telephone number (in the calling party field), the trigger criteria type (indicating the service for which the query is intended) and a presentation indicator in the calling party ID field.
SCP 107 checks the calling party""s presentation indicator in the calling party ID field, and determines whether that caller has a public number (i.e., it is not a private number) or a private number, or whether the caller is unknown. If the caller""s number is known and public, SCP 107 sends back a response (response 3 in FIG. 1a) instructing SSP 104 to terminate the call, and to supply the caller""s telephone number (and if the subscriber has subscribed to a higher level of service, the caller""s name and telephone number). In that case, SSP 104 terminates the call (call 1xe2x80x2 in FIG. 1a), i.e., completes the call, supplying the subscriber with the caller""s number (and possibly also with the caller""s name if the subscriber has subscribed to, e.g. caller ID deluxe which provides the caller""s name as well as the caller""s telephone number).
However, if the caller""s number is private, SCP 107 cannot authorize termination of the call without permission from the caller. In that case, the SCP""s response (response 3 in FIG. 1a) directs the call from SSP 104 to SN 109 via SSP 108 (call 4 in FIG. 1a). Under the standard AIN protocol BRI Q.931, the call carries with it three numbers: (1) the number of the original called party (in this case the subscriber); (2) the number of the re-directing party (also the subscriber in this case); and (3) the number of the calling party. SN 109 then engages in a dialog with the caller. SN 109 asks the caller for permission to override his/her privacy. The caller is asked whether he or she agrees to have his or her privacy overriden. If the caller answers yes (e.g., by pressing 1 on his or her telephone), SN 109 dials a Customized Dialing Plan (CDP) code followed by the calling party number and the called party number (call 7 in FIG. 1a). The CDP code triggers an Info_Analyzed query to SCP 107 (query 5 in FIG. 1a). SCP 107 then retrieves the calling party number and the called party number from the query, and responds by sending an Analyze Route message (response 6 in FIG. 1a) to SSP 108, with the subscriber""s number as the called party number. SSP 108 makes an outbound call (call 7xe2x80x2 in FIG. 1a) to the subscriber""s SSP 104. The number of the actual calling party is substituted in the calling party field.
This call triggers a second TAT query at SSP 104 to SCP 107 (query 8), asking for authorization to terminate the call to the subscriber. SCP 107 recognizes this call as originating from an SN, and accordingly responds (response 9) authorizing termination of the call to the subscriber (call 1xe2x80x2 in FIG. 1a), and release of the calling party""s number, so that the subscriber can accept or reject the call.
However, the subscriber""s line is also sometimes marked private. In that case, the SN does not have the subscriber""s telephone number, because BRI lines do not have access to the re-directing party number when a call is being forwarded from a private number (this is generally true for all systems using the AIN Release 0.0 architecture). Thus SN 109 cannot place call 7 back to the subscriber, because SN 109 no longer knows the subscriber""s telephone number.
Thus this system cannot terminate calls when both the calling party and the subscriber have private numbers, because the subscriber""s telephone number is no longer available when the SN tries to re-route the call to the subscriber.
The present invention is a system and method that allows calls to be completed to subscribers who have subscribed to a privacy screening service, even when the subscriber and the caller have private numbers, or when the subscriber number is private and the caller number is unknown. The present invention is illustrated in FIGS. 2a (for calls from a public number), 2b (for calls from an unknown number), and 2c (for calls from a private number), implemented in an AIN network similar to the AIN networks illustrated in FIGS. 1 to 1a. FIGS. 2a-2c show arrows indicating messagesxe2x80x94queries and responsesxe2x80x94from SSP 104 and SSP 108 to and from STP 106. These messages are all routed to and from SCP 107 as well (just like query 2 and response 3 in FIG. 1a), but, for simplicity, the continuations of the messages from STP 106 to SCP 107 are not shown in FIGS. 2a-2c. 
As shown in FIGS. 2a-2c, in all cases the calling party""s call is routed (as call 1 in FIGS. 2a-2c) through the caller""s SSP 103 to the subscriber""s SSP 104. The call hits the subscriber""s TAT, triggering a query (query 2 in FIGS. 2a-2c) which goes up to SCP 107 via STP 106. SCP 107 checks the calling party""s presentation indicator in the calling party ID field and determines whether the calling party""s number is public (i.e., nonprivate), private or unknown. If the calling number is public (the call flows for calls from a public calling number are shown schematically in FIG. 2a), SCP 107 sends back a response (response 3 in FIG. 2a) authorizing termination of the call to the subscriber. SSP 104 then terminates the call (call 1xe2x80x2 in FIG. 2a).
If the calling party is unknown (the call flows from an unknown calling party are shown schematically in FIG. 2b), response 3 in FIG. 2b (in a preferred embodiment) instructs SSP 104 to ask the caller whether he or she is willing to record his or her name, so that it could be played to the subscriber. For example, the caller is asked to press a xe2x80x9c1xe2x80x9d for xe2x80x9cyesxe2x80x9d or a xe2x80x9c2xe2x80x9d for xe2x80x9cno.xe2x80x9d SSP 104 collects the digit pressed by the calling party, and sends a Resource_Clear query (query 4) to SCP 107. SCP 107 reads the collected digit, and determines if the caller was willing to record his or her voice. If the calling party was not willing, the response (response 5 in FIG. 2b) instructs SSP 104 to disconnect the call. If the calling party was willing to have his or her name recorded, response 5 instructs SSP 104 to route the call to SN 109 via SSP 108 (call 1xe2x80x3 in FIG. 2b).
There is a termination attempt trigger provisioned on SN 109""s number at SSP 108. When the call hits that trigger, SSP 108 sends a query (query 6) to SCP 107, with the subscriber""s number in the redirecting party field. SCP 107 retrieves the subscriber""s number from the re-directing party field, and writes the number in the DisplayText field of its response (response 7) to SSP 108. SN 109 then prompts the calling party to state his or her name, and records the calling party""s name. After the calling party records his or her name, SN 109 dials a Customized Dialing Plan (CDP) code, followed by SN 109""s number and the subscriber""s number. The CDP code triggers an Info_Analyzed query (query 8 in FIG. 2b) from SSP 108 to SCP 107 with the SN""s number and the subscriber""s number in the collected digits field of the query. SCP 107 retrieves the SN""s number and the subscriber""s number from the collected digits field of the query, and returns an Analyze_Route response (response 9 in FIG. 2b) to SSP 108 with the SN""s number in the calling party field, the subscriber""s number in the called party field and the SN""s number in the charge number field. SSP 108 then routes the call to the subscriber via SSP 104 (calls 1xe2x80x2xe2x80x3 and 1xe2x80x2 in FIG. 2b). The call hits the termination attempt trigger provisioned on the subscriber""s line at SSP 104, triggering a query (query 10) back to SCP 107. SCP 107 recognizes the SN""s number in the charge number field, and authorizes termination of the call (response 11).
If the calling party number is private (the call flows for calls from private numbers are shown schematically in FIG. 2c), SCP 107 rewrites the presentation indicator in the calling party field as public, and in response 3 in FIG. 2c (in a preferred embodiment) instructs SSP 104 to ask the caller whether he or she is willing to have his or her privacy overriden. For example, the caller is asked to press a xe2x80x9c1xe2x80x9d for xe2x80x9cyesxe2x80x9d or a xe2x80x9c2xe2x80x9d for xe2x80x9cno.xe2x80x9d SSP 104 collects the digit pressed by the calling party, and sends a Resource_Clear query (query 4) to SCP 107. SCP 107 reads the collected digit and determines if the caller was willing to have his or her privacy overriden. If the calling party was not willing, the response instructs SSP 104 to disconnect the call. If the calling party was willing to have his or her name recorded, the response (response 5 in FIG. 2c) instructs SSP 104 to route the call to SN 109 (call 6 in FIG. 2c).
At this point, before the call is terminated from SSP 108 to SN 109, SSP 108 still has access to the subscriber""s telephone number (even if the subscriber""s number is private) in the re-directing party identification field. However, the subscriber""s number will be deleted from the re-directing party field when the call is terminated to SN 109.
The call to SN 109 at SSP 108 (call 6 in FIG. 2c) triggers the termination attempt trigger provisioned on SN 109""s number (just as in the case for unknown callers). This trigger prompts a query (query 7 in FIG. 2c) back up to SCP 107. SCP 107 retrieves the subscriber""s number from the re-directing party number field, and sends a response (response 8) to SSP 108 authorizing termination to SN 109, with the DisplayText field of the response populated with the subscriber""s number. SSP 108 sends the subscriber number on to SN 109 in a setup message. SN 109 then retrieves the subscriber""s number from the setup message and dials a Customized Dialing Plan (CDP) code, followed by a string consisting of the true calling party number and the subscriber""s number. The CDP code triggers an Info_Analyzed query (query 9 in FIG. 2c) to SCP 107 with the calling party number and the subscriber""s number in the collected digits field of the Info_Analyzed query. SCP 107 retrieves the calling party number and the subscriber""s number from the collected digits field, and returns an Analyze_Route response (response 10 in FIG. 2c) with the SN as the charged party and the subscriber as the called party.
SSP 108 then routes the call to the subscriber""s number at SSP 104. The call (call 6xe2x80x2) hits the termination attempt trigger provisioned on the subscriber""s line at SSP 104, triggering a query (query 11 in FIG. 2c) to SCP 107. SCP 107 recognizes the SN""s number in the charged party field, and authorizes termination to the subscriber (response 12 in FIG. 2c). The call is then terminated to the subscriber (call 1xe2x80x2 in FIG. 2c) and the subscriber is provided with the calling party""s telephone number (and name, if the subscriber has a service, such as caller ID deluxe, that provides the subscriber with the name as well as the telephone number of the calling party).
The DisplayText field used to store the subscriber""s number in the present invention is a field in the termination attempt query from SCP 107 to SSP 104. Ordinarily, the DisplayText field is used for providing, for example, calling party information on calls made to ISDN devices. The ten digits of the re-directing party/subscriber""s telephone number fits within the constraints of the DisplayText field (generally, up to 40 characters may be displayed on the telephone""s display).
Thus all calls from the SN to the subscriber will trigger two queries up to the SCP: first at SSP 108 and then at SSP 104. For calls from unknown calling parties, the SN remains on the call, even when the connection is made to the subscriber, because the SN has to play the recording of the calling party""s name for the subscriber. For calls from calling parties with private numbers, the SN drops out as soon as the subscriber""s telephone rings, because the SN no longer needs to be on the call.
Accordingly, it is an object of the present invention to provide a privacy screening service which allows calls to be routed to a subscriber to the service irrespective of whether the calling party number is public, unknown or private.